Fix comment from commit 22655aa231.

Per automated complaint from BF animal koel this needed to be
re-indented, but there was also a typo.  Back-patch to 16.

src/backend/access/heap/heapam.c

@@ -1803,10 +1803,10 @@ ReleaseBulkInsertStatePin(BulkInsertState bistate)
 	bistate->current_buf = InvalidBuffer;
 
 	/*
-	 * Despite the name, we also reset bulk relation extension
+	 * Despite the name, we also reset bulk relation extension state.
-	 * state. Otherwise we can end up erroring out due to looking for free
+	 * Otherwise we can end up erroring out due to looking for free space in
-	 * space in ->next_free of one partition, even though ->next_free was set
+	 * ->next_free of one partition, even though ->next_free was set when
-	 * when extending another partition. It's obviously also could be bad for
+	 * extending another partition. It could obviously also be bad for
 	 * efficiency to look at existing blocks at offsets from another
 	 * partition, even if we don't error out.
 	 */

src/backend/utils/misc/pg_controldata.c

@@ -24,6 +24,7 @@
 #include "common/controldata_utils.h"
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "storage/lwlock.h"
 #include "utils/builtins.h"
 #include "utils/pg_lsn.h"
 #include "utils/timestamp.h"
@@ -42,7 +43,9 @@ pg_control_system(PG_FUNCTION_ARGS)
 		elog(ERROR, "return type must be a row type");
 
 	/* read the control file */
+	LWLockAcquire(ControlFileLock, LW_SHARED);
 	ControlFile = get_controlfile(DataDir, &crc_ok);
+	LWLockRelease(ControlFileLock);
 	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
@@ -80,7 +83,9 @@ pg_control_checkpoint(PG_FUNCTION_ARGS)
 		elog(ERROR, "return type must be a row type");
 
 	/* Read the control file. */
+	LWLockAcquire(ControlFileLock, LW_SHARED);
 	ControlFile = get_controlfile(DataDir, &crc_ok);
+	LWLockRelease(ControlFileLock);
 	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
@@ -169,7 +174,9 @@ pg_control_recovery(PG_FUNCTION_ARGS)
 		elog(ERROR, "return type must be a row type");
 
 	/* read the control file */
+	LWLockAcquire(ControlFileLock, LW_SHARED);
 	ControlFile = get_controlfile(DataDir, &crc_ok);
+	LWLockRelease(ControlFileLock);
 	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));
@@ -208,7 +215,9 @@ pg_control_init(PG_FUNCTION_ARGS)
 		elog(ERROR, "return type must be a row type");
 
 	/* read the control file */
+	LWLockAcquire(ControlFileLock, LW_SHARED);
 	ControlFile = get_controlfile(DataDir, &crc_ok);
+	LWLockRelease(ControlFileLock);
 	if (!crc_ok)
 		ereport(ERROR,
 				(errmsg("calculated CRC checksum does not match value stored in file")));